The incident happened Monday night on a train headed toward North Station from Lowell.

Transit police at North Station were alerted to the situation by crew aboard the train. As the Lowell train came to a stop and passengers were getting off, the officers noticed the suspect, later identified as Mehmet Beyaztas, running down the platform and away from the train.

The officers were immediately notified by train personnel Beyaztas was the man who was involved in the incident on board the train.

The witness, a female on the train sitting across from Beyaztas, said the suspect made no attempt to conceal and/or be covert with his actions and his genitals were fully exposed.

Beyaztas was expected to be arraigned in Boston Municipal Court Tuesday.